opencv 图像阴影检测

源文：http://blog.csdn.net/abcjennifer/article/details/7334043

参数说明：

IplImage *workImg-当前全局变量,表示正在显示的图片。

downleft, upright- 检测出的阴影部分矩形框的两个对角顶点。

 /*********************************************/
  //阴影检测
 /*********************************************/

 CvPoint downleft,upright;
 int cnt;
 int dir[8][2]={-1,-1,-1,0,-1,1,0,1,0,-1,1,1,1,0,1,-1};
 #define SHADOW 170
 #define Thres_KindNumber 20

 bool InRange(CvPoint point,IplImage* pi)
 {
     int w=pi->width;
     int h=pi->height;
     if(point.x>=0&&point.x=0&&point.y
     {
         float  v[3];
         for(i=0;i<3;i++)
         {
             v[i]=((uchar*)(pi->imageData + pi->widthStep*point.y))[point.x*3+i];
             if(v[i]<=SHADOW)
                 return true;
         }
     }
     return false;
 }

 void Dye(IplImage** curimg,CvPoint s)
 {
     int i;
     queueQ;
     Q.push(s);

     for(i=0;i<3;i++)
         ((uchar*)((*curimg)->imageData + (*curimg)->widthStep*s.y))[s.x*3+i]=SHADOW+10;

     while(!Q.empty())
     {
         s=Q.front();
         Q.pop();

         if(s.x
         if(s.y
         if(s.x>upright.x)    upright.x=s.x;
         if(s.y>upright.y)    upright.y=s.y;

         //dye around
         for(i=0;i<8;i++)
         {
             CvPoint now=cvPoint(s.x+dir[i][0],s.y+dir[i][1]);
             if(InRange(now,*curimg))
             {
                 Q.push(now);
                 cnt++;
                 for(i=0;i<3;i++)
                     ((uchar*)((*curimg)->imageData + (*curimg)->widthStep*now.y))[now.x*3+i]=SHADOW+10;
             }
         }
     }
 }

 void CCVMFCView::OnShadowDetect()
 {
     //detect shadows,find the region with highest pixel value
     int x,y;
     srcimg=workImg;
     for(y=0;yheight;y++)
         for(x=0;xwidth;x++)
         {
             CvPoint curp=cvPoint(x,y);
             downleft.x=srcimg->width;downleft.y=srcimg->height;
             upright.x=upright.y=0;
             cnt=0;

             if(InRange(curp,srcimg))
                 Dye(&srcimg,curp);
             if(cnt>Thres_KindNumber)
                 cvRectangle(workImg , downleft,upright,CV_RGB(0,255,0),1,CV_AA,0);
         }
         Invalidate();
 }